There have been various types of closure systems for sterile medical liquid containers. Many of these closure systems included an inner cap and an outer cap that form double sterility protector seals. In most cases the outer cap was removed as a separate step prior to opening the inner cap. In some medical circumstances this procedure may be desired. Examples might include opening the outer closure prior to connecting an administration set to the inner closure.
However, there are certain circumstances where it is desired to simultaneously remove the inner and outer closures as quickly and easily as possible. An example would be where a container with a double closure system has a measured volume of liquid that is to be poured into another container. Here the entire liquid contents of the first container would be dispensed at once. Another example would be where a physician desires to dispense a measured quantity of liquid into a surgical wound or the like. Thus, a physician can completely empty a 1/2 liter bottle of liquid into the wound and have a much more accurate volume record than he could by pouring out 1/4 of the liquid contents from a 2 liter container.
With previous containers having double closure systems the nurse or physician often had to go through an intricate tedious series of steps to open the container. This problem was aggravated when numerous bottles had to be opened for a particular medical procedure.